June performance

June seemed to be in line with past year averages at least temperature-wise. (1 heating degree day less than the 10 year average, 52% less HDD than May, 8% more sun). We turned on the air conditioning for a couple of hours on three particularly hot and humid days. We’ve also started building a barn this month so that is starting to show up in our energy usage. This partially resulted in 5% higher energy usage in June. We used 0.36 kWh for space heating and 2.76 kWh for cooling. Our daily average usage was up 9% from May. We generated a 614 kWh surplus this month, our forth surplus month in a row and highest yet.

All values in kWh (except HDD)

Jan 20121

Feb 20122

Mar 20126

Apr 20127

May 20127

Jun 20127

Solar PV generation

369

597

860

925

867

939

Usage

873

666

515

378

309

325

Net usage or (generation)

504

69

(345)

(538)

(558)

(614)

Average daily usage

28.2

23.0

16.6

12.9

10.0

10.8

HDD (base temp 68F)3,4

1,2125

1,045

704

617

298

144

1 January values based on meter reads.2 February values based on TED data.3 Heating Degree Days (a measure of how many outside degrees in a day it is below a target inside temperature)4 Calculated from our HOBO outdoor weather monitor hourly data, unless otherwise noted.5 January HDD data downloaded from degreedays.net, Station ID: KALB (Albany International Airport).6 March values based on meter reads. (TED died March 1st, eMonitor installed March 16, 2012)7 Values based on eMonitor data.

Our ‘thermal comfort index’ is still quite high. The house generally maintains a cool temperature throughout the day without much window opening and closing. The evenings have been cool enough to lower the temperature of the house to stay comfortable for most of the day. This month was the first time we’ve used the air conditioning component of our ASHP. The unit is located on the first floor and definitely cools the first floor down very quickly. The upstairs did not cool down as quickly, although we have yet to run the air conditioner more than a few hours at a time. I suspect it will require more run time to cool off the upstairs. I’m sure we’ll find out in the next couple of months. Our ceiling fans make a huge impact on comfort.

June was also our first year anniversary for connecting the solar PV system to the grid, which means the electric company owes us a credit! But of course you have to pull some teeth to find someone to talk to about making sure the credit shows up on our account. I’m curious to find out what 3.65 MWh are worth at the ‘avoided rate’. I’m guessing a few cents a kWh, which would add up to roughly $100. We pay roughly $200/yr for connection fees. We’d have to get about 6 cents a kWh to get a credit of that size.

May was our third full month of circuit level data monitoring. All the data is available at netplusdesign.com. You can now view solar, usage, net usage, temperatures and HDD for all of February and circuit-level data for 16 days in March and the full months of April through June.